In the display industry, TFT (Thin Film Transistor) has been broadly applied as a switch element. For the category of metal oxide semiconductor, aluminum oxide (Al2O3) is usually utilized as one kind of material to form a gate insulator through anodization of aluminum on a display array substrate and further, in the peripheral area of the display array substrate, a thorough hole must be formed by etching the corresponding part of aluminum oxide (Al2O3) in order to expose an end of gate lines for electrically connecting to an outside of the display array substrate. However, it is difficult to increase the etching rate in order to improve the efficiency of manufacturing the display array substrate.